ML19329B186

Reactor Protection Sys Noise Testing Summary.

ML19329B186
Person / Time
Site:	Davis Besse
Issue date:	12/16/1976
From:	BABCOCK & WILCOX CO.
To:
Shared Package
ML19329B185	List: ML19329B184 ML19329B186
References
NUDOCS 8001300784
Download: ML19329B186 (3)

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RPS NOISE TESTING SEUIARY -

1.0 Noise Rejection and Tolerance of the RPS The Davis-Besse 1 Plant - RPS exhibite a high degree of innut '.ty to the effects of. clectromagnetic and elect'rostatic induced noise on 'non-1E signal output leads and class 1E input leads. The immunity to noise is established by:

1. Operating experience

2. Tests

3. Noise reject!on circuits .

1.1 Operatine Exnerience The- RPS for Davis-Besse I is similar to the RPS operating at:

1. Oconee 1, 2 and 3

2. Three Mile Island 1

3. Arkansas Nuclear 1=

4 Sacramento Municipal Utility District The record of these operating systems shcus no cases where the RPS vera precluded from performing their safety function due to the precence of noise that exists at these plants. Additionally, there are no instanccc whera incdvertent initiation of the RPS safety function occurred due to the presence of noise.

1.2 Tests The RPS equipment van tested at the following test bcds to determine the system ability to perform its safety function in environments sicilar to nuclear power plants.

1. Lvnchburg Research Center

2. Cleveland Illumination Company - Eastlake Plant

13. Diamond Power Specialty Company These tests confirned the noise rejection circuit i.esign of the RFS.

1.2.1 .Lvnchbure Research Center (Attachment #1)

A cabinet containing the neutron flux channels uns tested for two years at

- the B&U Lynchburg Research Center. The channel processed simulated inputs, neutron inputs from a graphite pile, and neutron inputs from the Lynchburt Research Center pool reacter. I=portant modules tested uithin the cabinet were the linear amplifiers, bistables, system power supplics, and detcetor

. power supplies. The test. proved the ability of tha system to function as de-l signed in a simulated nuclear peuer plant ' environment. l 80.01300f8g l

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> 1'. 2. 2 Cleveland Illuminating Company - East Lake Plant Test (Attachment #2)

The East Lake Plant is. a fossil pcuer . generating station containing high electrical energy equipment. A cabinet containing signal processing equip-

.nent and bistables was installed for a period of two weeks. In this. test,

. the input cables were deliberatley routed as close as possibic to the electrical equipment described below to provide a severe EMI environment. The electrical equipment was operational and soce transient operation of the electrical equip-ment occurred during the test interval. During the test interval, the bistchle .

setpoints vere maintained within 0.020 volts of the simulated input signal.

The test results showed the channel generated protection signals when. required, no inadvertent protection signals were generated and no component "ailures were discovered. The East Lake test proved the ability of the system to function as designed in an environment considered nore severe than a nucles ,wer plant installation.

- 18 K VAC, 3,500 ampere main generator output busses

- 2300 VAC; 12, 28, 35, 38, 50,120, 230, 400, and 750 a peres circuits serving suitchgear, cable trays, =otors 480 VAC, 50, 60 and 115 ampere pcuer circuits and fan loads.

- 375 VDC, 930 ampera e:: citer

' 300 VAC,12, 35, 38 a= pere 11ghting, circuit pcaer circuits, crusher equipment, and electrostatic precipitators.

1.2.3 .Diacond Pouer Snecialtv Comenny Tests (Attachment #3)

Diamond Power Specialty Cc=pany provides the control rod drive control system.

The control rod drive system accepts 480 VAC, 240 a= peres and provides 125 VDC, 8 ampere square waves to the control red drive techanists. A cabinet containing signal processing equipment and bistables was installad for a paried of two veeks. In this test, the simulated input cables were deliberately routed as close as possible to 480/120 VAC,'250 KVA transformer, 120 VAC/125 VDC pcuer supplies, and the 125 VDC, 8 ampere square wave paaer cables. The signal processing codulas contained rate of changa c=plifiers and bist:bles. The test results showed the channel generated protection signals when required, oc inadvartent protection signals were genercted, and no cerpenent failures occurred. The test preved the ability of the system to function in an EMI envirennent containing 60 li: and switching transients.

'l.3 Noise Reiection Circuits The RPS' contains built-in noise rejection circuits to prevent icproper operatien due to signals induced by EMI. All digital logic is cade frcn

. relays. Transient voltages produced by EMI would have to have an a=plituda approaching the operating patential of the relay (15 VDC) and a duration long enough.(25 ncec) to cause the drop out of energi:cd relays. EMI induced trcnsient would have to bridge open ' control centact to cause da-energized relays to pick up. Relays are noted for inherent aoisa it= unity to trcesients

-induced by EMI. Analog signal patas are' eriginated with sensors that nrevide

.a current signal. proportional to the process par:1:eter 'conitored. The current signal monitoring method minimines the cifects of EMI. Additionally t.he utnalog signal processing =odules and'histables contain lou pass input 3$ "Y W

X e-filter'notuorks. : Typical _ modu'le _attenuat' on values for a 60 H signal are

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. provids.d - below. When'the nodules are combined to form an instrument string, the combined a ' ttenuation'is realized. The lou pass filter circuit provide increased attenuation as.the frequency of_the E1I induced signal increases.

The greater the transient rate,fthe greater the~ attenuation.

- The bistable module is .the last' analog signal processing module in an instrument' string. The bistable compares the measured process parameter

' to -a_ setpoint; if ' the setpoint is reached, Ja digital channel trip signal is it.itiated. The bistable provides the majority of analog signal noise attenuation,: location' of -the ' majority of the at tenuation at the end of the instrument string assures that noise induced upstream in the string from any

. source vill be attenuated by the bistable and produce minimum effect on the system operation.

liodule 60 H: Attenuation. db Buffer Anplifiers -8 Flou Summer .-13

'Heutron Flux Channel - Power Range -13.5 Square P.oot extractors -8 Bf ', table -34 i

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